Abstract: The polyaluminosiloxane was prepared through cohydrolysis condensation.The flame retardant mechanism of the polyaluminosiloxane for polycarbonate(PC) was studied by limited oxygen index, thermogravimetric analysis, scanning electron microscopy, and energy dispersive X-ray spectroscopy(EDX). It was found that the polyaluminosiloxane improved the limiting oxygen index of PC. In the thermal degradation process with 5 mass% loading of polyaluminosiloxane, the thermal degradation rate was reduced, and the char yield at 800 ℃ was increased by 44.1 %. During the combustion process, the polyaluminosiloxane would migrate to surface and interact with PC degradation product to promote the formation of carbon residue. The accumulation of Si and Al on the surface enhanced the carbon layer which retarded further pyrolysis of the material and hinder the transmission of heat and combustible gases, and thus improved the flame retardant effect.

Key words: polycarbonate, polyaluminosiloxane, flame retardant, thermal degradation